The Lethal Effect of Some Natural Plants Extracts on Tobacco cutworm Spodoptera litura (Lepidoptera: Noctuidae) and their Relative Toxicity

Abstract

In view of the environmental and health problems caused by industrial pesticides and their negative impact on various aspects of life, the attention of researchers and specialists has turned to natural alternatives that contain effective compounds in control insects. The present study tested the effect of four natural plant extracts (Nerium oleander, Melia azedarach, Ocimum basilicum and Mentha arvensis) in mortality the third-age larvae of the tobacco leaf-cutworm (Spodoptera litura). The results showed a variation in mortality rates depending on the type of extract, concentration, and date of taking the reading. The extracts of the M. azedarach fruits were significantly superior to the leaves of the M. azedarach and the leaves of N. oleander, where the averages reached 47.22, 37.20, and 33.83%, respectively, while the extracts of M. arvensis and O. basilicum showed relatively low mortality rates. The mortality rates also increased over time, reaching 53.31% at 96 hours after treatment, while it was 24.39% at 48 hours, which indicates the Antifeeding behavior of these natural substances, which is similar to the action of compounds such as azdrachtin. It can be said that these natural pesticides can be good tools in pest management programs.